/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:		arm_scale_q31.c
*
* Description:	Multiplies a Q31 vector by a scalar.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupMath
 */

/**
 * @addtogroup scale
 * @{
 */

/**
 * @brief Multiplies a Q31 vector by a scalar.
 * @param[in]       *pSrc points to the input vector
 * @param[in]       scaleFract fractional portion of the scale value
 * @param[in]       shift number of bits to shift the result by
 * @param[out]      *pDst points to the output vector
 * @param[in]       blockSize number of samples in the vector
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format.
 * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.
 */

void arm_scale_q31(
    q31_t *pSrc,
    q31_t scaleFract,
    int8_t shift,
    q31_t *pDst,
    uint32_t blockSize)
{
    int8_t kShift = shift + 1;                     /* Shift to apply after scaling */
    int8_t sign = (kShift & 0x80);
    uint32_t blkCnt;                               /* loop counter */
    q31_t in, out;

#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */

    q31_t in1, in2, in3, in4;                      /* temporary input variables */
    q31_t out1, out2, out3, out4;                  /* temporary output variabels */


    /*loop Unrolling */
    blkCnt = blockSize >> 2u;

    if(sign == 0u)
    {
        /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
         ** a second loop below computes the remaining 1 to 3 samples. */
        while(blkCnt > 0u)
        {
            /* read four inputs from source */
            in1 = *pSrc;
            in2 = *(pSrc + 1);
            in3 = *(pSrc + 2);
            in4 = *(pSrc + 3);

            /* multiply input with scaler value */
            in1 = ((q63_t) in1 * scaleFract) >> 32;
            in2 = ((q63_t) in2 * scaleFract) >> 32;
            in3 = ((q63_t) in3 * scaleFract) >> 32;
            in4 = ((q63_t) in4 * scaleFract) >> 32;

            /* apply shifting */
            out1 = in1 << kShift;
            out2 = in2 << kShift;

            /* saturate the results. */
            if(in1 != (out1 >> kShift))
                out1 = 0x7FFFFFFF ^ (in1 >> 31);

            if(in2 != (out2 >> kShift))
                out2 = 0x7FFFFFFF ^ (in2 >> 31);

            out3 = in3 << kShift;
            out4 = in4 << kShift;

            *pDst = out1;
            *(pDst + 1) = out2;

            if(in3 != (out3 >> kShift))
                out3 = 0x7FFFFFFF ^ (in3 >> 31);

            if(in4 != (out4 >> kShift))
                out4 = 0x7FFFFFFF ^ (in4 >> 31);

            /* Store result destination */
            *(pDst + 2) = out3;
            *(pDst + 3) = out4;

            /* Update pointers to process next sampels */
            pSrc += 4u;
            pDst += 4u;

            /* Decrement the loop counter */
            blkCnt--;
        }

    }
    else
    {
        /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
         ** a second loop below computes the remaining 1 to 3 samples. */
        while(blkCnt > 0u)
        {
            /* read four inputs from source */
            in1 = *pSrc;
            in2 = *(pSrc + 1);
            in3 = *(pSrc + 2);
            in4 = *(pSrc + 3);

            /* multiply input with scaler value */
            in1 = ((q63_t) in1 * scaleFract) >> 32;
            in2 = ((q63_t) in2 * scaleFract) >> 32;
            in3 = ((q63_t) in3 * scaleFract) >> 32;
            in4 = ((q63_t) in4 * scaleFract) >> 32;

            /* apply shifting */
            out1 = in1 >> -kShift;
            out2 = in2 >> -kShift;

            out3 = in3 >> -kShift;
            out4 = in4 >> -kShift;

            /* Store result destination */
            *pDst = out1;
            *(pDst + 1) = out2;

            *(pDst + 2) = out3;
            *(pDst + 3) = out4;

            /* Update pointers to process next sampels */
            pSrc += 4u;
            pDst += 4u;

            /* Decrement the loop counter */
            blkCnt--;
        }
    }
    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
     ** No loop unrolling is used. */
    blkCnt = blockSize % 0x4u;

#else

    /* Run the below code for Cortex-M0 */

    /* Initialize blkCnt with number of samples */
    blkCnt = blockSize;

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

    if(sign == 0)
    {
        while(blkCnt > 0u)
        {
            /* C = A * scale */
            /* Scale the input and then store the result in the destination buffer. */
            in = *pSrc++;
            in = ((q63_t) in * scaleFract) >> 32;

            out = in << kShift;

            if(in != (out >> kShift))
                out = 0x7FFFFFFF ^ (in >> 31);

            *pDst++ = out;

            /* Decrement the loop counter */
            blkCnt--;
        }
    }
    else
    {
        while(blkCnt > 0u)
        {
            /* C = A * scale */
            /* Scale the input and then store the result in the destination buffer. */
            in = *pSrc++;
            in = ((q63_t) in * scaleFract) >> 32;

            out = in >> -kShift;

            *pDst++ = out;

            /* Decrement the loop counter */
            blkCnt--;
        }

    }
}

/**
 * @} end of scale group
 */
